If you have the LiteEditor project open, and gdb is installed, simply running the debugger should work. However you'll avoid potential confusion if you use a different configuration in the debuggee. You can do that with recent CL versions by adding:--datadir=/path/to/another/.codelite
in the 'Project Settings > General > Debug program arguments' field.

The problem I still encounter is that I need to provide images during the install process (they should go in /usr/lib/codelite/resources).
I don't know how to achieve this with CMake... once again, I need help.

Untested, but I think that just adding your images to Runtime/plugins/resources/ will work. There's a line in LiteEditor/CMakeLists.txt that installs everything in Runtime/plugins/resources/ to /usr/lib/codelite/resources/.

Since the file 'codelite-plugin.cmake' (see the previous link for learning about codelite-plugin.cmake file) is a CMake file, you can add extra cmake code to it.
For example, if you want to install extra file to codelite's share folder (Linux):

The following example, shows how to install the entire content of the 'ScriptPlugin/resources' (if you had such a folder...) into /usr/share/codelite/ScriptPlugin